Lubricator for earth boring drills



May 16, 1933. F L. SCQTT 1,909,078

LUBRICATOR FOR EARTH BORING DRILLS` Filed July 17, 1950 7 #if f- K se,Wm H73 am.

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Patented yMay 16, 1933 N UNITED STATES non L. sco'r'r, lor' nous'rox.muxas, assIeNoa 'ro Buenas. groozlconrm. or t v PATENT' FFC '7HOUSTON,`TIXAB, A CCBPORLTION '0F TEXAS anneau mea .my 17,

Myinvention relates to means for lubrieating' the cuttersof roller earthboringr dril Drill cutters on roller drills em loyed in dee welldrilling must be designe to work at t e bottomof wells of greatdepthwhere v the static pressure of the liquid in the hole is very great. Oilwells a mile or more indepth are now common. As a result of these heavyliquid pressures on the outside of the cutter v bearings, the mud in thehole tends to force itself into the bearings of the cutters even beforethe cutters are rotated. It is found that even where the cutter bearingsare completely filled with lubricant before the drill is inserted intothe well, there is suicient air in solution in the lubricant to allowcompression n by the` outer liquid sufficiently to permit entrance ofmud to the bearings in the usual type of lubricator.

Also when the drill is operating, the bushings will wear'and lpermit alay of the cutter upon the bushing, whic breathing or pum ing actiontending to suck the mud into the arings. In this way, the

. action of the' lubricant is greatly counteracted and heatingandexcessive wear result.

lt is an object of my invention to l provide a lubricator which'.wi1lovercome the defects above set out. I desire to prevent the entrance ofmud to the bearings and to equalize the liquid pressures on both sidesof the bearings so that mud will not tend to enter.

I aim to provide a small lubricant chamber in thehead of the drill andto permit approximatel the same' pressure at the upper n rienced at thel side of the ubricant "as is e lower side of the lubricant c cutter. lf l.

Referring to the drawing; Fig. 1 is a ver' tical section' through acutter of` `common construction shown in position upon one-half annelsandthe of the .bit head and having my invention applied thereto.v

' Fig. 2 `is a side elevation of the half of the bit head shown in Fig.1.

Fig. 3 is a sectional detail showing the lubricant chamber on the plane3-'3 o Fig. 1.

' The drill shown is a hard formation bit having rolling cutters 1thereon of approxiresults in a mao. y aum ne. 46am.

mately fragte-conical shape. .The yhad [is made up `of two sectionsQadapted'to fit'tof gether along the flattened faces3." There aregrooves 4 longitudinally of these `faces' 3, which when re' isteredtogether forma longitudinal liqui passage axiall offthe head. The uppershank of the head 1s threaded at 5 to engage the drill collar.

Thecutters 1 are 4mounted upon shafts 6 integral with the-head and uip dwith conical bushings 7 over whizl'lH t shells are fitted. The innerends of the bushings 7 have a reduced neck `8 and a retaining' This ringacts to prevent the entrance of mud tothe bearing `surfaces ofthecutter. l

Iprovide a lubricator including a cylin-l drical- 12 bored downwardlyfromA the flat face 3 of the'head atan angle' thereto and terminatingabove the shaft 6.y A Aduct 13` leads from said recess through the shaft6 to a lubricant channel 14 in the bushing and to the cutter bearings.

As will be best seen in Fig. 3, I have a piston in saidrecess; saidpiston including two packing cups 15 facing in opposite directions. Said.cups are fitted rupon a bolt 16 and clamped between two Cplaftesll'lglhere'rlil by a o t e t. e up.-

nut 18 on the lower en per end of the recess has a threaded plug 19screwed therein. Said plug has a longitudinal opening 20 kto allowentrance of liquid in the well suiciently to equalize the liquid.

pressure at both ends of the lubricant passage. An opening from theoutside at 21 allows liquid to enter above the piston.

In the use of my invention, the liquid ressure is equalized so as toprevent a ten ency of the mud to enter about the bearings.k Suchpressure as is exerted around the outside of the cutter bearings isequalized by the liquid entering ,behind the plunger or ypiston 15.

Thus the packing ring 11 will seal off the entrance of mud to the bearins.

In the o ration of the dr1ll,when the bushings have come slightly worn,the umping action of the cutter moving out an in upon the bushing willtendV to pump lubricant from the recess12 to the bearings, and this willbel permitted by the piston 15, which is wei hted by the bolt and theplates or washers 1 and tends to jar down by gravity and move thelubricant below it to the bearlng surfaces. It ,is obvious that thepiston can be forced back also by any pumping action of the cutter onthe bushings, and there will be no tendency 15 to suck mud in about theseal ring 11.

The life of the bushings will be rolonged by this structure and also theease o handling the present lubricaton compared with the older typeswill be facilitated.

What I claim as new is: 4

1. In a roller well drill, a head, a non-rotatable cutter shaft thereon,a cutter rotatably mounted on said shaft, means for conducting lubricanttothe bearing surfaces be-f tween the cutter and the shaftz and a.packing ring, U shaped in cross section, engaging both the cutter andthe shaft and having its convex side facing toward bearing surfaces. y y

2. In a roller well drill, a head, a non-rotat-V able cuttershaftthereon, a cutter rotatably mounted on said shaft, a lubricant chamberin said head, means to equalize the fluid pressure thereon, means forconducting lubricant from said chamber to the bearing surfaces betweenthe cutter and the shaft, and a packing ring, U shaped in cross section,engaging bothv the cutter and the shaft and having its convex sidefacing toward said bearing surfaces.

40 In testimony whereof, I hereunto ailix m signature, this 12th day ofJul A. D., 193

L FLOYD SCOTT.

